1. Field of the Invention
The invention relates to the field of surgical instruments. In particular, it relates to a surgical instrument for use in general and minimally invasive surgery.
2. Description of Related Art
It is advantageous in the field of general or minimally invasive surgery to perform operative interventions with an instrument that provides a proximal handle capable of being opened with one or with two hands and a distal tip that can be positioned and manipulated with precision. A surgical sliding shaft instrument is capable of being used in this manner. The sliding shaft apparatus of a surgical instrument permits the positioning and action of the distal tip to be effected by maneuvers of the proximal handle. A surgical sliding shaft instrument includes a slide that is axially displaceable on the shaft. Commonly, the slide can be displaced proximally and distally on the shaft by the operator's opening or closing the legs of a handle. This can allow the operator to control the placement of the distal tip of the shaft with the same hand that displaces the slide proximally or distally, although the instrument can also provide a handle best activated with two hands. The motion of the slide takes place as the legs of the handle pivot with respect to one another. As the slide moves proximally or distally, it may engage other parts of the surgical instrument and cause their displacement. For example, the sliding mechanism can actuate a mechanism for providing a punch biopsy, a mechanism that acts as a rongeur or a mechanism for grasping tissues or objects.
In order to clean and sterilize a surgical instrument consisting of several movable pieces, it is desirable that the instrument be capable of dissasembly. This allows each component to be cleaned and sterilized separately, so that each surface achieves maximum asepsis. In a sliding shaft instrument, such dissasembly can require the slide being separated from the shaft. An example of a sliding shaft instrument capable of disassembly is described in DE 4316768 A1. In the instrument described in this patent, the slide is mounted on the shaft by swallowtail guides. When the slide is displaced into a retracted position on the proximal portion of the shaft, the swallowtail guide is disengaged and the slide can be removed from the shaft. The shaft of this instrument is permanently connected to a first handle leg. The second pivotable handle leg is affixed to the slide. The second handle leg is held in place by a cross pin that engages an open-ended slot of the second handle leg. As long as the slide is affixed to the second handle leg by its cross pin, it cannot be moved into the proximal end position that would permit it to be separated from the shaft. In order to disassemble the sliding shaft instrument, the articulation pin connecting the two handle legs is pulled out, so that the handle legs are no longer connected with one another. The cross pin is then removed from the pivotable handle leg. This frees the slide, so it can be slid into its proximal end position. Once in this position, the swallowtail guide can be disengaged from the shaft. The instrument according to this patent comes apart in four pieces, permitting cleaning and sterilization of the component parts of the instrument. However, the disassembly and subsequent reassembly of the sliding shaft is time-consuming and cumbersome. Further, there is the risk of component parts getting lost. The articulation pin is particularly vulnerable to misplacement. Without this component, the device cannot be reassembled.
A sliding shaft instrument is described in DE 19513572 A1 in which a pivotable member is mounted on the proximal end of the slide and is brought into engagement for coupling with the pivotable handle leg. By pivoting this member outward, the coupling connection between the slide and the handle leg can be released. Once released, the slide can be moved into position on the proximal end of the shaft so that it can be separated from the shaft. In this instrument, the handle legs do not have to be separated from one another. The pivotable member and its lock are mechanically complex, however. This raises problems of adequate cleaning and sterilization, since the components cannot be fully detached.
Therefore, there remains in the art a need for a surgical sliding shaft instrument that permits easy cleaning and sterilization, without undue risk of loss of the components once disassembled. Furthermore, it is desirable that the device be mechanically simple, so that disassembly and reassembly is not unduly burdensome or time-consuming. A further desirable feature of the instrument is a slide that can be removed and reinstalled without further disassembly of the sliding shaft. It is also desirable to provide a control mechanism for a surgical device that allows precise placement of the distalmost portion of the shaft and precise control of the action of the sliding shaft.